The present invention relates to coated abrasives and specifically to coated abrasives with an abrasive surface that has been engineered to provide a plurality of individual structures comprising a cured binder having dispersed therein abrasive particles. These structures can be made by a molding, embossing or a patterned deposition approach. Each however provides a structure with the advantages of an open coated abrasives with separate abrading points, space for the swarf generated to be removed from the immediate abrading area, and fine finish resulting from the use of relatively fine abrasive particles.
Engineered abrasives are coated abrasives in which the abrasive surface is in the form of repeating shapes comprising abrasive particles dispersed in a cured binder disposed on a backing material. In general the performance of these products depends on the contours of the repeating shapes which frequently have the form of structures that diminish in width with distance from the plane of the backing. The shapes can be in the form of parallel ridges, pyramids with square or triangular bases, or somewhat rounded shapes. Coated abrasives of this type are described for example in U.S. Pat. Nos. 5,014,468; 5,152,917; 5,454,844; 5,489,235; 5,672,097; 5,681,217; 5,833,724; 5,840,088; and 5,863,306. Within these variations it is possible to vary the size, spacing, frequency of repetition and so on of the structures, as well as the materials used to form the structures.
The abrading structures comprising such engineered abrasive surfaces are usually made using binders that are radiation-curable resins and may further comprise additives such as fillers, plasticizers and grinding aids. Many of these can yield unpleasant odors when the engineered abrasive is used to abrade a substrate and heat is generated as a by-product. This is particularly true of xe2x80x9cwater-proofxe2x80x9d products that are intended for use in applications in which water is used either to sweep away swarf or as a coolant.
The object of this invention is to overcome negative reactions to an engineered abrasive product by neutralizing the unpleasant odors and rendering the experience of using the engineered abrasive at the same time a satisfying experience from both the technical and the olfactory viewpoints.
The present invention provides an engineered abrasive comprising a backing and, applied thereto, at least one abrasive-containing layer engineered to provide a plurality of individual abrasive composite structures, said engineered abrasive having incorporated therein a composition including an additive with a pleasant fragrance. While it is understood that xe2x80x9cpleasingxe2x80x9d is often a matter of subjective judgment, in the context of this Application the word is intended to refer to fragrances that are generically regarded as pleasing such as floral, musk or citrus fragrances. However it should also be understood that, as part of a promotional program or to address local cultural prejudices as to what constitutes xe2x80x9cpleasantxe2x80x9d, other fragrances such as those of beer, cigar smoke or new-mown grass might be substituted.
The fragrance can be applied to the backing where this is of an absorbent nature such as a paper or cloth material. More preferably however it is incorporated as a component of an abrasive/binder precursor slurry from which are formed the individual abrasive composite structures that make up the engineered abrasive surface. Alternatively it may be applied as a component of a layer applied to the surface of the abrasive/binder slurry before or after the individual composite structures are formed.
The fragrance can be added as a liquid but this is generally not favored since the liquid tends to be lost during production of the engineered abrasive rather than be liberated during use. It is therefore preferred to add the fragrance absorbed on a porous powder carrier or encapsulated in a membrane that can be ruptured under grinding conditions. The membrane can be glass or plastic or ceramic for example. The material is less important than the ability to rupture when the engineered abrasive is in use and not during the production process.
The amount of the fragrance added should not be more than 5% by weight of any layer to which it is added. Preferably the amount is from 1 to 3% of such weight. The weight referred to includes the weight of any carrier or encapsulation that accompanies the fragrance. This is because the added material usually has minimal contribution to the grinding performance of the product and may indeed negatively impact the performance to the extent that it is displacing abrasive material from the formulation. It is most preferred to incorporate the fragrance absorbed into a porous form of a grinding aid such as potassium fluoroborate or cryolite. For example it is known to add grinding aids in the form of agglomerates of the powdered grinding aid loosely held together by a binder material. Absorbing the fragrance into such an agglomerate provides an agglomerated additive with the dual function of assisting the efficiency of the grinding and at the same time releasing the pleasant fragrance. Equally the carrier could be an agglomerate or other porous form of another useful additive.